title: Differentiating developmental outcome between infants with severe disability in research studies: the role of Bayley Developmental Quotients.
abstract: OBJECTIVE
  To investigate whether infants with a score <50 on the Bayley Scales of Infant Development, Second Edition (BSID-II) demonstrated differences in functional ability, and to assess whether the Bayley Developmental Quotients (DQs) indicated such differences.
  
  
  METHODS
  Preterm infants (n = 67; 47 boys) with posthemorrhagic ventricular dilatation were evaluated at 25 months past term age using the BSID-II and grading of functional ability. Mental and Motor Bayley DQs were derived and compared with functional ability.
  
  
  RESULTS
  Among the 34 subjects (51%) with a BSID-II score <50, there were clinically significant differences in the ability to walk, sit, eat, speak, and see. In all subjects, there were significant differences in Mental and Motor Bayley DQs based on grade of disability in each domain except hearing.
  
  
  CONCLUSIONS
  Bayley DQ quantified the spread of functional ability in all children, provided a continuous parameter to compare ability in severely delayed children, and should be considered in future therapeutic trials of infants with brain injury.
authors.affiliation: School of Clinical Sciences, University of Bristol, Bristol, United Kingdom. sally.jary@bristol.ac.uk
authors.forename: Sally
authors.initials: S
authors.lastname: Jary
authors.forename: Grazyna
authors.initials: G
authors.lastname: Kmita
authors.forename: Andrew
authors.initials: A
authors.lastname: Whitelaw
mesh_terms: D002657:Child Development; D002675:Child, Preschool; D002658:Developmental Disabilities / Q000175:diagnosis / Q000523:psychology / Q000534:rehabilitation*; D006233:Persons with Disabilities; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D011594:Psychometrics / Q000379:methods*; D011795:Surveys and Questionnaires